4,234 research outputs found

    Boundary effects on the scaling of the superfluid density

    Full text link
    We study numerically the influence of the substrate (boundary conditions) on the finite--size scaling properties of the superfluid density ρs\rho_s in superfluid films of thickness HH within the XY model employing the Monte Carlo method. Our results suggest that the jump ρsH/Tc\rho_s H/T_c at the Kosterlitz--Thouless transition temperature TcT_c depends on the boundary conditions.Comment: 2 pages, 1 Latex file, 1 postscript figure, 2 style file

    Assessing moisture in porous traditional building materials

    Get PDF
    Historic England is often asked for advice on damp problems in historic and traditional buildings. Whilst many different methods are commonly used to assess damp problems in walls, all have some drawbacks. There is lack of agreement over how they should be used and little information about how they compare one with another. This project developed a common methodology in the laboratory to compare the performance of a range of invasive and non-invasive moisture measurement methods used to assess moisture in porous masonry. The findings suggested that most of the measurement techniques can provide good semi-quantitative estimates of moisture levels in porous traditional building materials

    Sorting live stem cells based on Sox2 mRNA expression.

    Get PDF
    PMCID: PMC3507951This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.While cell sorting usually relies on cell-surface protein markers, molecular beacons (MBs) offer the potential to sort cells based on the presence of any expressed mRNA and in principle could be extremely useful to sort rare cell populations from primary isolates. We show here how stem cells can be purified from mixed cell populations by sorting based on MBs. Specifically, we designed molecular beacons targeting Sox2, a well-known stem cell marker for murine embryonic (mES) and neural stem cells (NSC). One of our designed molecular beacons displayed an increase in fluorescence compared to a nonspecific molecular beacon both in vitro and in vivo when tested in mES and NSCs. We sorted Sox2-MB(+)SSEA1(+) cells from a mixed population of 4-day retinoic acid-treated mES cells and effectively isolated live undifferentiated stem cells. Additionally, Sox2-MB(+) cells isolated from primary mouse brains were sorted and generated neurospheres with higher efficiency than Sox2-MB(-) cells. These results demonstrate the utility of MBs for stem cell sorting in an mRNA-specific manner

    Decentralised Learning MACs for Collision-free Access in WLANs

    Get PDF
    By combining the features of CSMA and TDMA, fully decentralised WLAN MAC schemes have recently been proposed that converge to collision-free schedules. In this paper we describe a MAC with optimal long-run throughput that is almost decentralised. We then design two \changed{schemes} that are practically realisable, decentralised approximations of this optimal scheme and operate with different amounts of sensing information. We achieve this by (1) introducing learning algorithms that can substantially speed up convergence to collision free operation; (2) developing a decentralised schedule length adaptation scheme that provides long-run fair (uniform) access to the medium while maintaining collision-free access for arbitrary numbers of stations

    Scaling of the superfluid density in superfluid films

    Full text link
    We study scaling of the superfluid density with respect to the film thickness by simulating the xyx-y model on films of size L×L×HL \times L \times H (L>>HL >> H) using the cluster Monte Carlo. While periodic boundary conditions where used in the planar (LL) directions, Dirichlet boundary conditions where used along the film thickness. We find that our results can be scaled on a universal curve by introducing an effective thickness. In the limit of large HH our scaling relations reduce to the conventional scaling forms. Using the same idea we find scaling in the experimental results using the same value of ν=0.6705\nu = 0.6705.Comment: 4 pages, one postscript file replaced by one Latex file and 5 postscript figure

    A Novel Liver-targeted Testosterone Therapy for Sarcopenia in Androgen Deprived Men With Prostate Cancer.

    Full text link
    Objective: Androgen deprivation therapy (ADT) reduces muscle and bone mass, increasing frailty in men with prostate cancer. The liver mediates the whole body anabolic effects of testosterone. Based on first-pass metabolism, liver-targeted testosterone treatment (LTTT) entails oral delivery of a small dose of testosterone that does not raise peripheral blood testosterone levels. LTTT reduces blood urea and stimulates protein anabolism in hypogonadal men and postmenopausal women. We investigated whether LTTT prevents loss of lean and bone mass during ADT. Method: A 6-month, double-blind, placebo-controlled study of testosterone 40 mg/day in 50 men. Primary outcome measures were lean mass and bone mineral content (BMC). Testosterone, urea and prostate-specific antigen (PSA) were monitored. Patients were withdrawn if PSA exceeded 4 ng/mL. Results: 42 patients completed the study. Mean (95% CI) testosterone rose during LTTT but not placebo treatment [∆ 2.2 (1.3-3.0) vs -0.7 (-1.5 to 0.2) nmol/L; P < 0.01]. Mean PSA level did not change significantly during either treatment. Blood urea fell [∆ -0.4 (-0.9 to -0.1) mmol/L] during LTTT but not placebo [∆ 0.05 (-0.8 to 0.9) mmol/L]. BMC [∆ 49 (5 to 93) g; P < 0.02] and lean mass [∆ 0.8 (-0.1 to 1.7) kg; P = 0.04) increased compared to placebo. Five patients on LTTT withdrew from increased PSA levels, all returning to baseline levels. Conclusion: LTTT shows promise as a simple therapy for preventing sarcopenia and bone loss during ADT. LTTT may induce reversible PSA rise in some patients. Further studies are required to optimize LTTT dose in ADT. LTTT has potential application in other catabolic states in men and women

    Angle-resonant stimulated polariton amplifier

    Get PDF
    We experimentally demonstrate resonant coupling between photons and excitons in microcavities which can efficiently generate enormous single-pass optical gains approaching 100. This new parametric phenomenon appears as a sharp angular resonance of the incoming pump beam, at which the moving excitonic polaritons undergo very large changes in momentum. Ultrafast stimulated scattering is clearly identified from the exponential dependence on pump intensity. This device utilizes boson amplification induced by stimulated energy relaxation
    corecore